Heart disease is a leading cause of death in the United States. Some patients may benefit from long-term ECG monitoring outside of a clinical setting. For example, atrial fibrillation and myocardial ischemia may occur episodically. Some episodes may occur without patient symptoms. Myocardial ischemia, if persistent and serious, can lead to myocardial infarction (heart attack). During a myocardial infarction, electrophysiological changes may be detected by an ECG. For accurate diagnosis and effective treatment of many episodic heart conditions, medical professionals need to receive accurate and timely information regarding the frequency and duration of such episodes.
In conventional long-term ECG monitoring, such as with continuous Holter monitors or event monitors, mounting of the monitor typically involves preparation of the patient's skin to receive the monitoring device. Chest hair may be shaved or clipped from men. The skin is abraded to remove dead skin cells, and cleaned. A technician trained in electrode placement applies the electrodes to the skin with an adhesive. Each electrode of such conventional monitors is attached to an insulated wire that is routed some distance across the patient's body to an amplifier designed to amplify the ECG signal in preparation for further processing. Such monitoring systems are often worn by a patient for up to a month.
Traditional long-term monitoring systems like those described above present a number of problems. For example, abrading in preparation for electrode mounting often leaves the patient's skin irritated. During use, the patient must be careful not to pull on the wires connected to the electrodes, lest the electrodes be pulled off the skin. Removing an electrode with its strong adhesive may be painful to the patient. Furthermore, certain types of electrodes require use of a gel next to the skin to improve conductivity at the point of connection of the metal electrode to the skin. Prolonged exposure to the gel can irritate the skin. These and other discomfort factors associated with traditional long-term monitoring solutions may discourage a patient from using the ECG monitor as directed by medical personnel.
Alternative health monitoring system designs exist that attempt to address the many shortcomings of traditional ECG monitors. For example, some monitor implementations known in the art are based on an article of apparel designed to be conveniently and comfortably worn by the patient, such as a wrist band. However, the patient typically must press down on common wrist band monitors to get a reading, which can be uncomfortable and error-prone. Also for example, some monitors are implemented as a finger ring equipped with sensors and data communications means, such as the following.
U.S. Pat. No. 5,964,701 to Asada et al. discloses a system comprising a sensor incorporated in a finger ring so as to monitor skin temperature, blood flow, blood constituent concentration, or pulse rate of a patient. Measured physiological data are encoded for wireless transmission to a remote processor by a battery-powered transmitter.
U.S. Pat. No. 6,402,690 to Rhee et al. discloses a health monitoring system characterized by an inner ring that carries sensor units, and an outer ring that carries a circuit board and battery unit. The outer ring may rotate by some kind of external force, while the inner ring remains largely stationary relative to the finger of the patient.
U.S. Patent Application No. 2012/0130203 by Stergiou et al. discloses an inductively-powered biosensor comprising a wrist element and a ring element. The wrist element may generate a current through one or more loops, thus creating a magnetic flux that the ring element may convert into power and also data communication using radio frequency (RF) induction technology.
U.S. Pat. No. 6,413,223 by Yang et al. discloses a cuffless continuous blood pressure monitor comprising first and second sensing bands that are displaced from each other along a ring finger of a patient. A sensor fusion scheme using Kalman filters is applied to indirectly estimate arterial blood pressure by integrating simultaneous sensor measurements taken by the two bands.
What is needed is a physically-worn, adjustable ECG monitor system that improves patient compliance with ambulatory cardiac monitoring. Such a system should be both comfortable to wear and easily to operate to achieve reliable results. Such a system also should feature physical separation of sensors, as wells as improved contact with a patient's body, to achieve better signal reading. Automated methods associated with such as system should account for latency due to separation of sensors. Such systems and automated methods should be cost efficient to manufacture to achieve broader distribution of the ECG monitoring solution.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.